filibuster, n. fil·i·bus·ter \ˈfi-lə-ˌbə-stər\
1: an irregular military adventurer; specifically : an American engaged in fomenting insurrections in Latin America in the mid-19th century
2 a : the use of extreme dilatory (see dilatory 1) tactics (as by making long speeches) in an attempt to delay or prevent action especially in a legislative assembly
b : an instance of this practice
Examples:
The filibuster delayed the voting on the bill for over a week.
They engaged in a filibuster that lasted for over a week.
More details, and notable examples of filibuster, can be found in this Wikipedia article:
Filibuster in the United States Senate Etymology
Spanish filibustero, literally, freebooter
First Known Use: 1851